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Paris (AFP) - The Solar System has at least two more planets waiting to be discovered beyond the orbit of Pluto, Spanish and British astronomers say. The official list of planets in our star system runs to eight, with gas giant Neptune the outermost. Beyond Neptune, Pluto was relegated to the status of "dwarf planet" by the International Astronomical Union in 2006, although it is still championed by some as the most distant planet from the Sun. In a study published in the latest issue of the British journal Monthly Notices of the Royal Astronomical Society, researchers propose that "at...

Presently, our solar system is known to contain 4 fully-fledged rocky worlds: Mercury, Venus, Earth and Mars; 2 ice-giants: Neptune and Uranus; 2 gas-giants, Saturn and Neptune; 5 dwarf-planets, Ceres. Pluto, Eris, MakeMake, Haumea; around 100 moons; and an unknowable number of comets, asteroids and minor planets. Indeed, we’ve only begun to understand the full scope of our local corner of our galaxy, and new information emerges on a monthly-basis, yet there a number of seemingly obvious things that remain unknown. For instance, long before Pluto’s existence was deduced, astronomers scoured the outer solar system in search of another large...

In their studies, the team analyzed the effects of what is called the ‘Kozai mechanism,’ which is related to the gravitational perturbation that a large body exerts on the orbit of another much smaller and further away object. They looked at how the highly eccentric comet 96P/Machholz1 is influenced by Jupiter (it will come near the orbit of Mercury in 2017, but it travels as much as 6 AU at aphelion) and it may “provide the key to explain the puzzling clustering of orbits around argument of perihelion close to 0° recently found for the population of ETNOs,” the team...